CET EKG Technician Skills and Knowledge Base 2 — Questions and Answers
Question 1: Which lead placement error would cause an inverted P wave in lead I?
- Right and left arm electrodes reversed (Correct answer)
- Right leg and left arm electrodes reversed
- V1 placed too high on the chest
- Left leg electrode placed on the abdomen
Correct answer: Right and left arm electrodes reversed
Reversing the right and left arm electrodes inverts the polarity of lead I, causing a negative P wave where it should be positive.
Question 2: A patient has a heart rate of 150 bpm with narrow QRS complexes and no visible P waves. Which rhythm is most likely?
- Atrial flutter
- Atrial fibrillation
- Junctional tachycardia (Correct answer)
- Ventricular tachycardia
Correct answer: Junctional tachycardia
Junctional tachycardia presents with a rate of 100–180 bpm, narrow QRS, and absent or retrograde P waves.
Question 3: What is the normal PR interval range on an adult EKG?
- 0.06–0.10 seconds
- 0.12–0.20 seconds (Correct answer)
- 0.20–0.28 seconds
- 0.04–0.08 seconds
Correct answer: 0.12–0.20 seconds
The normal PR interval is 0.12–0.20 seconds (3–5 small boxes), representing atrial depolarization and AV node conduction.
Question 4: During a Holter monitor application, why is it important to abrade the skin before attaching electrodes?
- To increase patient discomfort as a reminder to wear the monitor
- To remove dead skin cells and oils that increase impedance (Correct answer)
- To mark electrode placement sites for later reference
- To sterilize the skin and prevent infection
Correct answer: To remove dead skin cells and oils that increase impedance
Light skin abrasion removes the outer epidermal layer and oils, lowering electrical impedance and improving signal quality.
Question 5: Which of the following is a characteristic of first-degree AV block?
- Some P waves are not followed by a QRS complex
- PR interval greater than 0.20 seconds with every P wave conducted (Correct answer)
- Progressive PR lengthening until a QRS is dropped
- Complete dissociation between P waves and QRS complexes
Correct answer: PR interval greater than 0.20 seconds with every P wave conducted
First-degree AV block is defined by a consistently prolonged PR interval (>0.20 s) with every P wave followed by a QRS.
Question 6: Which precordial lead is placed at the 4th intercostal space, right sternal border?
- V1 (Correct answer)
- V2
- V3
- V4
Correct answer: V1
V1 is placed at the 4th intercostal space along the right sternal border, directly to the right of the sternum.
Question 7: A QRS complex wider than 0.12 seconds most commonly indicates:
- Bundle branch block or ventricular origin (Correct answer)
- First-degree AV block
- Sinus bradycardia
- Atrial enlargement
Correct answer: Bundle branch block or ventricular origin
A wide QRS (≥0.12 s or 3 small boxes) indicates delayed ventricular conduction, as seen in bundle branch blocks or beats originating in the ventricles.
CET EKG Technician Skills and Knowledge Base 2
Which lead placement error would cause an inverted P wave in lead I?